This invention relates to improvements in plumb bobs, especially for indicating a point on the ceiling or other elevated portion of a room in direct alignment with a designated point on the floor or other lower portion of the room. It is applicable particularly in indicating a point on the ceiling directly over a corresponding point on the licor.

In laying out and installing uorescent lights or other types of lighting fixtures, it has been diiiicult heretofore to locate the fixtures at the desired point on the ceiling, with respect to a particular point on the floor. The only means available heretofore for doing this has been the use of a plumb bob suspended by a string, but this is very tiresome because of the necessity for holding the string' by hand, which makes it necessary to suspend it for several minutes while the plumb bob stops swaying. Moreover, it is diflicult to use in some locations, especially in open buildings, where the wind would interfere with the use of the plumb bob.

The object of this invention is to improve the construction of plumb bobs, to enable theseto be used in any desired place, without diiiiculty, and without the strain and labor ordinarily involved heretofore in obtaining a particular location for a fixture.

This object is accomplished, according to a preferred embodiment of the invention, by utilizing a beam of light suspended from a lamp supported loosely in a. universal joint so as to act as a plumb bob and to project the beam of light to a desired point. This enables the user to obtain the location quickly and without the labor and diculty of suspending a plumb bob on a string, This is particularly applicable when locating or laying out a lighting Xture in a set position with respect to the iioor. It can be used also to level conduit risers and switchboards, slide rails on elevator shafts, and other objects that must be plumb.

According to this embodiment of the invention, by way of example, a weighted member is attached to a projecting tube that encloses an electric lamp for projecting a beam of light through the tube. The tube is suspended on a universal joint7 so as to be centered automaticallyin an upright position which is absolutely vertical,`with the light projecting upwardly, so as to indicate a point on the ceiling or upper portion of the structure directly over and in vertical alignment with the corresponding point on the floor.

This embodiment is illustrated in the accompanying drawings, in which:

Fig. l. is a side elevation of the plumb bob as an embodiment of the invention;

Fig. 2 is a similar view at right angles thereto;

Fig. 3 is a vertical sectional view therethrough on the line 3--3 of Fig.,2; l

Fig. 4 is a horizontal sectional view on the line 4-4 of Fig. l;

Fig. 5 is a similar View Fig. l;

Fig. 6 is a detached perspective View of the lens tube; N l

Fig. 7 is a similar view of the lamp support; and

Fig. 8 is a vertical sectional View through the lower portion of the lamp device showing a modification therein. In `the form illustrated in the drawings, a plumb bob structure includes aibase designated generally by the numeral l, substantially U-shaped, as shown in Fig. 5, with lateral arms adapted to embrace the `selected point on the licor.` Upstanding from the base l, is a standard 2, for supporting the operating parts of the plumb bob. The lower end `of the standard 2 is Xed to the base i, while the upper end thereof forms a support for the operating parts.

As shown in Figs. 1 `and 4, a yoke 3 extends laterally from the upper end of the standard 2 and issecured rigidly to the standard by a screw 4, which extendsthrough the standard and into a side of the yoke 3, that is inabutting relation against a side of the standard, forming a clamped connection between the yoke and the standard.

The-opposite arms `of the yoke 3 carry pointed pins 5 in opposed relation to each other, each of which `pins is threaded through an arm of the `yoke for adjustment relative thereto, and has a lock nut thereon. The pins 5 engage a support and mounting ring l on diametrically opposite sides of said ring for1freedom of swinging movement ofthe ring relative to the yoke 3. Similar `pivot pins are shown at 8, to those desigria-ted` 5, `as described, but are `arranged at right angles to the pins 5 and coacting therewith and with the mounting ring 'l to form a universal joint. i

Suspended by the universal joint isa lamp device carried directly on the pins 8, engaging the lamp device at opposite sides for freedom of swinging movement relative to the pins 81, while the `latter and ring 1 are also `free to swingen the pointed pins 5; This assures the location of the lamp device in an absolutely vertical position by the action of gravitythereon.

In the form illustrated as an embodiment of on the line 5-5 of 'lamp "casing,

lwill be evident from the drawings, vweighted bob is notrequired for this purpose howeven but mercury or other Weighing means -may be contained in the housing-section I9, as indicated at 28 in Fig. Spin-which event the lamp Q u the invention, the lamp device includes a mounting tube 9, and a lens tube I9, shown as telescoped with respect to each other for relative vertical adjustment by a pin II, engaging in a slot I2 in the tube I9, the pin il being shown as a screw attached to the tube 9. This screw may be used to lock the tubes in set positions with respect to each other, if desired. The tube 9 is engaged at-opposite sides by bearings therein with the pins 8.

A lens is shown at I3 at the upper end of the tube 9, and an additional lens is shown at I4 at the lower end of the tube |0, the lens I4 being mounted in a lens holder E5, detachably secured by a set screw I6 to the lower end of the tube I9. An additional lens is shown at I1, below the lens I4, although the number and character of these lenses may be varied as desired, according to the desired qualities of the beam of light to be pro- .lected A lamp housing is shown as formed by sections I8 and I9, telescoped with each other and detachably secured to each other, 4as by screw threading, friction, or other suitablemanner. A lamp socket 29 is mounted in the housing I8-I9,

lwith a reector `2I extending outwardly therefrom and adapted for detachable connection of an eleotricflight bulb 22, Withthe socket 29. The socket 29 is shown as mounted by means of a 'spring'ba'il"23, attached to the reflector 2| and frictionally engaging the inner wall of the housing I8.

While any desired provision may be made for `energizing 'thelamp22, either from batteries, house current, etc., I have shown-as an example,

the connection of the socket 2] through a wire V'f'ffilttobatteries'25 mounted in a holder 26 on the vstandard'Z, vas means for electrically energizing the lamp. One side of the batteries may be grounded to the Abase I, as shown, while the opposite side of the lamp will be grounded to the Any suitable provision may be made in the wire 24, for controlling the energizing ofthe lamp, as by switch means or the like.

The' lower end of the lamp structure preferably should be weighted so as to hold the tubes S-Ifl 'in a yvertical'position, as well as to act as -a `pointer f for the device.

A weighted bob is shown at 21, in Figs'l and 2, attached to the lower end of the lamp housing section I9; in position to be located in close kproximity to the 'door or other` support upon which the structure may be supported, Vas 'A separate housing, preferably, is pointed at its lower lend `as indicated at 29.

The use of the devices will be evident from the foregoing description. When it is desired to 'dctermine a point onthevceiling of aroom, as an exampleywith respect to a particularflocation on the iioor, it is necessary merelyto set the instrument on the-'iioor with the bob 21, or'the pointed end 29 of the lamp structure, directly over the "desired point. rvThe universal mounting 5-8 al- -lowsthe lampdevice to hang in `-a verticalA position, whereupon the energizing of the lamp 22 `will project a beam of light vertically to a vpoint on the ceiling Vdirectly over thenset point on the L floor beneath the pointed'bob'Z'l or 29. The action of'vgravity'issufcient to enable the device to assume a vertical position corresponding in action with'that ofa vpluii'lbloob Suspende'dn.

lto

a string, but without the labor and difficulty normally encountered in holding such a plumb bob. Moreover, the set position may be determined much quicker and more easily than has been possible heretofore With a string supported plumb bob, as well as permitting the use of this instrument in many locations where an ordinary plumb bob could not be used.

The instrument can be used also as a surveyors instrument by placing it on a stand with a level attached to one side to indicate the level position of the instrument when the light beam will indicate the desired reading.

`While the invention has been illustrated and described in certain embodiments, it is recognized that variations and changes may be made therein, without departing from the invention, except as specified in the claims.

I claim:

l. As a means for selectively indicating overhead'service locations, wherein such location is `remote from the indicating source and requires unrestricted access thereto to permit unrestrained service activities at the overhead location point,

portable assemblage adapted to be selectively 'positioned on a supporting surface located below Aand remote from the service location and to direct a true vertical light-ray beam to said overhead location to spot-light the'point of service application, said assemblage comprising a portable support including a vertical standard, a light-ray projecting instrumentality carried by and suspended within an upper Zone of the standard with the point of suspension above the mid zone of the instrumentality, said instrumentality including the light ray projecting means and having a .weighted lower end zone swingingly movable relativeto .the portablesupport and operative to con- .trol the position .and direction of the instrumen- .tality axis, said lower end. Zone being pointed with the point approaching the lower plane of the `portable support, the point and the light-ray beam both extending on and being located in ythe instrumentality axis to thereby permit location of the assemblage on and positioning of the freely swingable pointedv end in the vicinity of the supporting surface to thereby permit selec- .tive positioning of suchpointed end relative to a predetermined selected point on the supporting surface vwith the projected beam extending in true'vertical alinement with the selected point and thereby enable the beam to transfer the position of the selected point location to the overhead location and thereby indicate the point of service application.

`2. An assemblage as in claim l characterized in 'that the support includes an open-ended 'forked base member having its forks positioned to permit free swinging movements of the pointed end within and between the forks of the base member, said base member carrying such vertical standard in rear of the forks, said v-standard carrying a gimbal mounting for supporting the instrumentality within the upper zone of the instrumentality and with the girnbal mounting active to permit free swinging of the Ainstrumentality pivotally with the swinging movements of the universal type to thereby per- ,mit support accommodation to the conditions of the surface on which the support is mounted. 3. fAn assemblage as in claim l characterized that the weighted zone of the instrumentality is -in the form of a weighted element of conical contour with its larger dimension uppermost to constitute the elements as of plumb-bob characteristic with the upper end having means for rigidly securing the element to the lower end zone of the instrumentality, said element having a pointed free end axially alined with the instrumentality axis.

4. An assemblage as in claim 1 characterized in that the instrumentality includes a tubular portion adjustable as to length and having a lens formation at its upper end, said portion also having a lens assembly at its opposite end adapted to focus light rays through said upper end lens, the instrumentality having a hollow lower zone equipped with a lamp assembly located axially and constituting a source of light rays to be emitted through the several lenses, said lamp assembly including a lamp socket carrying a reflector with the latter carrying a spring bail adapted to engage side walls of the hollow lower zone.

5. An assemblage as in claim l characterized in that the instrumentality includes a tubular portion adjustable as to length and having a lens formation at its upper end, said portion also having a lens assembly at its opposite end adapted to focus light rays through said upper end lens, the instrumentality having a hollow lower zone equipped with a lamp assembly located axially and constituting a source of light rays to be emitted through the several lenses, said tubular portion being formed of a pair of telescoping sections adjustably connected below the suspension point.

RAYMOND ROBERT ESI-IER.

REFERENCES CITED The following references are of record in the le of this patent: